Those “addicted” to Harry Potter, the titular hero of the Harry Potter series of books, have the same level of addiction as drug addicts have and suffer from almost the same withdrawal symptoms.

The book series has come to an end with the title Harry Potter and the Deathly Hallows.

The hard-to-believe finding is the result of research by Professor Jeffrey Rudski of Muhlenberg College, Pennsylvania, the United States, and colleagues.

In the study, appearing in the Journal of General Psychology, the researchers compared the craving for cigarettes to the "craving” by fans for Harry Potter books, the phenomenally best-selling and popular creations by J K Rowling.

They wrote in the Journal of General Psychology, “After finishing the series, 10% of fans spent over four hours a day on Harry Potter-related activities, experiencing withdrawal symptoms like interference with appetite and sleep, engaging in less physical activity, having a lower sense of well-being and being more irritable. And, 20% of the fans are on the verge of addiction.”

“An addiction to a drug,” added Prof Jeffrey Rudski, “is no different from an addiction to the child wizard Harry Potter or the internet or pornography. Some readers can become so engaged in the series and the ancillary world that grew out of it that they report behaviors that truly fit definitions of addiction or dependence. In short, addiction to a drug is no different to an addiction to Harry Potter.”

The seventh and final book of the series, Harry Potter and the Deathly Hallows, published in the summer of 2007, sold a record 400,000,000 copies. Of the 4,000 Harry potter fans polled, many admitted to having spent up to 4 hours a day on “Potter-related activities.”

The Mirror newspaper of the United Kingdom quoted one Harry Potter fan as lamenting, after knowing that the character would not appear in any more books: “I feel like someone close to me has died.”

The Harry Potter series began in 1997 with the publication of Harry Potter and the Philosopher’s Stone. After the colossal commercial success of the character the world over, movies based on series began to be made starting 2001.

In the movies, Daniel Radcliffe plays Harry Potter.

Harry Potter and the Half-Blood Prince, the sixth installment in the movie version of the series, will be released in November 2008.